All Questions
17
questions
2
votes
1
answer
221
views
Can we have positively curved space within negatively curved spacetime?
Thinking about the universe as a whole. One could imagine that the three spatial dimensions each have the same, say positive, curvature, making space spherical, while time is negatively curved, making ...
- 371
1
vote
1
answer
59
views
Curvature sign-changing Friedman models
Isotropy and homogeneity of space leads to the spacetime metric of the form
$$
ds^2=-dt^2+d\sigma_k^2,
$$
where $d\sigma_k^2$ is the metric on one of the standard manifolds (the 3-sphere, Euclidean 3-...
- 421
0
votes
2
answers
60
views
Does the increasing rate of expansion of the universe have any implication on or alter the curvature of the universe?
I'm not really knowledgeable on physics but was curious about this and couldn't find any good answers related to it.
- 3
2
votes
2
answers
124
views
Measuring the Hubble constant in a curved universe
In an article from the University of Chicago, July 17, 2020, it is stated that
"Judging cosmic distances from Earth is hard. So instead, scientists measure the angle in the sky between two ...
- 24.8k
1
vote
2
answers
490
views
Curvature of spacetime in Friedman cosmological models
Short version of my question is as follows: What is curvature of spacetime (rather than space) in Friedman cosmological models?
Now the long version, including evolution of my thoughts and background ...
- 2,173
0
votes
1
answer
56
views
Does cosmological expansion change the gravitational field around a massive body?
Do expanding universe affect the curvature of spacetime? If so, does Einstein's field equation account for the change in curvature (gravitational field) around massive object in the expanding universe?...
- 31
1
vote
1
answer
281
views
Curvature in space time during Big Bang and present scenario
Space time in the presence of masses is curved. But during the time of Big Bang it's presumed that all the matter in this universe was at a single point, so it must have been super dense and had very ...
6
votes
2
answers
5k
views
Why is the hypersphere not seriously considered by cosmologists as the best model for the overall shape of the universe?
Cosmologists seem to not seriously consider the hypersphere as the best model for the universe even though they mention it as a candidate from time to time. If you look closely, it seems to be a very ...
- 97
-4
votes
3
answers
870
views
Can the fabric of space-time be contoured into hills instead of just wells? [closed]
Einstein's general theory of relativity states that gravity is the distortion of space-time into gravity wells. In order to illustrate this, a flat plane is used to represent undistorted space-time ...
- 1,066
0
votes
1
answer
126
views
The curvature of our universe?
When someone says that the universe is flat it should be infinite. But, this contradicts the Big bang because infinity can never be reached from below. If the universe is in fact infinite then shouldn'...
- 327
2
votes
3
answers
267
views
When a massive object warps the space around it, does the amount of space expand?
I may have watched those physics shows for too long, but the warping of space is usually described as a surface which bends. Whenever that happens, the surface they are showing increases in surface ...
- 21
3
votes
1
answer
133
views
Will the flatness of spacetime decrease with the expansion of the Universe?
My question specifically, how has the curvature of the universe remained just about flat topologically as the universe has expanded and thus if the expansion of the universe is accelerating then ...
- 2,958
-1
votes
1
answer
193
views
Is space time curvature an effect of "slowed" local expansion? - Is a gravity field 'drag' in the cosmic expansion?
I've been trying to intuit what gravity is actually doing in respect to spacetime for a while. I'm familiar with the technical descriptions the relevant equations present but I'm trying to form more ...
8
votes
2
answers
875
views
Can shape of the universe change?
Is it possible for a closed [spherical geometry] Universe to evolve to become an open [hyperbolic geometry] Universe?
- 989
0
votes
0
answers
83
views
Can we see enough of the universe to have a valid opinion on whether it's expanding?
Let me preface by saying I know very little about cosmology but have been wanting to learn. I'm a mathematician specializing in hyperbolic $3$-manifolds, and am aware of some of the applications of ...
- 361